[threeseed]

There is nothing inherently special about ARM that makes it use less power.

Apple simply invested a huge amount of resources and had the benefit of optimising the SOC specifically for the OS.

[fmajid]

Which is why Intel is an also-ran in mobile computing and IoT despite all the ressources it poured into it, I suppose?

The sheer amount of legacy in x86 is why those CPUs are so inefficient and require so much cooling. ARM would not have emerged if not for its superior efficiency.